Horn having resonating chambers at antinodal points



9 14, 1931- M. R. HUTCHISON 1,814,554

HORN HAVING RESONATING CHAMBERS AT ANTINODAL POINTS Original Filed May24, 1927 INVENTOR. Mz'Z/er Reese Hufc/uson.

A TTORNEY Patented July 14, 1931 UNITED STATES PATENT QFFICE MILLERREESE HUTCHISON, OF LLEWELYN PARK, WEST ORANGE, NEW JERSEY, AS-

SIGNGR, BY MESNE ASSIGNMENTS, TO ACOUSTIC PRODUCTS COMPANY, CF NEW YORK,N. Y., A CORPORATION OF DELAWARE HORN HAVING RESONA'IING CHAMBERSANTINODAL POINTS Application filed. May 24, 1527, Serial No. 193,814.Renewed December 2, 1930.

This invention relates to sound propagating devices of the type in whicha column of air is set into vibration by a mechanical diaphragm.

' In devices where the column of air is contained in a horn-shapedmember at the neck of which a diaphragm is located, the horn operates ina manner similar to an open end organ pipe which is resonant to waveshaving a length double that of the pipe. It is well known that such apipe will reinforce vibrations set up by a tuning fork of the rightpitch to such a degree that they become audible at a considerabledistance therefrom while notes of other frequencies produce nonoticeable effect.

The diaphragm of an electromagnetic unit located at one end of a hornoperates similar to such a tuning fork and sets up 20 vibrations orwaves in the medium contained therein. frequency to which the horn isresonant they will be reinforced and amplified thereby whereas othernotes are discriminated against.

This invention provides means for increasing the selectivity of the hornto such a degree that it will not respond to unclesired impulses, suchas static, while permitting the horn to respond freely to both itsfundamental and the various over-tones thereof.

The invention provides a substantially open end pipe having a mechanicaldiaphragm operatively associated therewith for imparting vibrations tothe medium contained therein. The gaseous medium such.

as air in such a pipe vibrates with a nodal point at the center andantinodal points at the two ends. Resonators are therefore introduced atthe antinodal points and are designed to respond to notes of thefundamental frequency of the pipe and to the various overtones thereofbut not to notes of other frequencies and particularly to notes of lowerfrequencies, such'as static. A plurality of such devices may beemployed, each device being tuned to a separate note of the chromaticscale in order to provide for the accurate and undistorted repro- Ifthese waves are of the duction of the entire musical range offrequencies.

The invention also consists in certain new and original features ofconstruction and combinations of parts hereinafter set forth andclaimed.

Although the novel features which are believed to be characteristic ofthis invention will be specifically pointed out in the claims appendedhereto, the invention itself, as to its objects and advantages, the modeof its operation and the manner of its organization, may be betterunderstood by referring to the following description taken in connectionwith the accompanying drawingsforming a part thereof in which likereference characters have been used to denote like parts in the variousfigures. Since such illustration is, however, primarily for purposes ofdisclosure, it will be understood that the structure and the method ofoperation thereof may be modified in various respects without departingfrom the broad spirit and scope of the invention.

One embodiment of the invention has been shown for purposes ofillustration in the accompanying drawings, in which Fig. 1 is adiagrammatic illustration of a sound propagating device constructed inaccordance with this invention, with a resonator at one antinodal point.

Fig. 2 shows a device having a resonator at each antinodal point andFig. 3 shows a plurality of such devices tuned to different frequencies.

In the following description and in the claims the various parts of theapparatus and details of the invention will be identified by specificnames for convenience, but they are intended to be as generic in theirapplication as the art will permit.

Referring to the drawings more in detail,

the invention is shown in Fi 1 as comprising a pipe 1, of suitablelength to resonate to a definite note in the chromatic scale. Anelectromagnetic unit 2 of any desired form having a movable diaphragm 3is secured to one end of said pipe, the diaphragm being adapted tooperate on the column of air located within said pipe for causingcompressions.

At one antinodal point of said pipe adjacent electro-magnetic unit 2 isattached resonator 4 which is preferably of substantially sphericalshape. Bell shaped horn 5 is located at the end of pipe 1 furthest fromelectromagnetic unit 2 for facilitating the propagation of the soundwaves to the surrounding medium.

In the device shown in Fig. 2 the parts are similar to those shown in land have been given similar reference numerals. A resonator 4 is howeverlocated at the open end on the horn. Resonators 4 and 4: are thus at thetwo antinodal points and operate in the manner to be hereinafterexplained.

In the operation of this device when vibrations of the frequency towhich pipe 1 is resonant are impressd upon diaphragm 3, sound waves areproduced in the air contained in pipe 1 and are reinforced thereby.lVhenevcr vibrations of other frequencies, however, are impressed upondiaphragm 3 they are not reinforced and the sound waves produced therebywill not be amplified by the resonant qualities of said pipe.Consequently the ratio of the amplitude of the desired musical notes tothat of the undesired notes is increased and the effect produced ofsuppressing such undesired notes.

The above mentioned air waves in passing through the pipe are reflectedat the two encs thereof and produce substantially stationary waveshaving a nodal point at the center of the pipe, and loops or antinodalpoints at the two ends. Resonators 4 and 4- being located at theseantinodal points and tuned to the fundamental frequency of the pipe willreadily respond to notes of this frequency and further increase theamplitude of the corresponding sound waves. Such resonators are sharplyselective and re spend but slightly to notes of other frequenandparticularly to notes lower than that to which they are tuned, such asfor example, notes produced by static in a. radio receiving set. Thedevice therefore, serves selectively to amplify notes of the fundamentalfrequency of the pipe and over-tones thereof and to suppress notes ofall other frequencies.

In order to amplify notes over the entire musical scale, a plurality ofresonating devices as described above may be employed as showndiagrammatically in Fi 3, each being tuned to a different note in oneselected octave. The parts are similar to those of Fig. 2 and arecorrespondingly numbered.

The twelve notes in an octave are thus reinforced by twelve resonatorsand since each is resonant to harmonics of its fundamental frequency,the various octaves comprising the complete range of musical frequenciesmay also be reproduced thereby.

It is thus necessary to employ a bank of only twelve resonating horns inaccordance with this invention to accurately reproduce music withoutintroducing distortion or discrimination against certain notes. Thehorns are however, sharply selective of their resonant frequencies anddo not reinforce other waves such as for example, these produced bystatic or spark disturbances.

The device therefore, in addition to being an eliicient means forpropagating line musical notes serves to suppress all undesired waves.Not only static eliminated but other disturbances which would interferewith the music or produce distortion thereof are suppressed.

lVhile certain novel features of the invention have been shown anddescribed and are pointed out in the annexed claims, it will beunderstood that various omissions, substitutions and cl'ianges in theforms and details of the device illustrated and in its operation may bemade by those skilled in the a rt without departing from the spirit ofthe inven tion.

lVhat is claimed is:

l. A sound propagating device comprising a vibrating diaphragm, atubular member associated. therewith and adapted to form an air columnresonant to waves of a definite frequency, said column having nodal andantinodal points, and a resonator located at one of said antinodalpoints tuned to the same frequency as said tubular memher.

2. A sound propagating device comprising a vibrating diaphragm, atubular member associated therewith and adapted to form an air columnresonant to waves of a. definite frequency, said column having nodal andantinonal points, and resonators located at said antinedal points tunedto the same frequency as said tubular member.

8. An acoustic device comprising a tubular member adapted to form an aircolumn resonant to waves of a definite frequency whereby nodal andantinodal points are formed, and a resonator tuned to said f're-.

quency located at an antinodal point in said column for reinforcing saidwaves and suppressing undesired noises.

4. A sound propagating device comprising an open end tubular memberresonant to waves of a definite frequency, means for producing soundwaves in sald member and resonators tuned to said frequency located atthe antinodal poi in said tube, whereby waves of the fundamentalfrequency and overtones thereof may be amplified and propagated, andwhereby waves of other frequencies may be suppressed.

5. An acoustic device comprising an open. tubular member resonant tovmves of a definite frequency, means for producii'ig sound waves in saidmember and spherical resonators located at the ends of said tubes tunedto the same frequency as said tubular member whereby waves of thefundamental frequency and overtones thereof may be amplified andpropagated, and whereby waves of other frequencies may be suppressed.

6. A device for propagating sound waves comprising an actuating unithaving a vibrating diaphragm, a tubular member associated therewith andadapted to form a resonating column, a resonator located at each end ofsaid member tuned to the same frequency as said tubular member, and ahorn secured to the resonator furthest from said actuating unit, saidassembly being capable of reproducing waves of a definite frequency andovertones thereof, and being substantially non-responsive to Waves ofother frequencies.

7. A device for propagating sound waves comprising a tubular memberadapted to form a resonating column, a resonator located at each end ofsaid member tuned to the same frequency as said tubular member, anactuating unit having a vibrating diaphragm located adjacent one of saidresona-tors, and a bell shaped horn secured to the other of saidresonators, said assembly being capable of reproducing waves of adefinite frequency and overtones thereof, and being substantiallynon-responsive to waves of other frequencies.

8. A sound propagating device comprising a plurality of actuating unitshaving vibrating diaphragms associated therewith,

tubular members associated with said diaphragms and adapted to formresonating hambers, said chambers being of different lengths andrespectively tuned to different notes of the chromatic scale and to thesame note as the associated tubular member, and resonators located atthe antinodal points of said chambers for selectively amplifying wavesof certain frequencies while suppressing waves of other frequencies.

9. A sound propagating device comprising a plurality of actuating unitshaving vibrating diaphragms associated therewith, tubular membersassociated with said diaphragms and adapted to form resonating chambers,said chambers being of difierent lengths and respectively tuned todifferent notes of the chromatic scale and to the same note as theassociated tubular member, and resonators located at the ends of saidchambers for selectively amplifying waves of certain frequencies whilesuppressing waves of other frequencies.

1.0. A sound propagating device comprising a plurality of actuatingunits having vibrating diaphragms associated therewith, tubular membersassociated with said diaphragms and adapted to form resonating chambers,said chambers being of different lengths and respectively tuned todifferent notes of the chromatic scale, and means located at theantinodal points in said chambers resonant to fundamentals of therespective chambers for selectively amplifying waves of said frequencieswhile suppressing waves of other frequencies.

11. A sound propagating device comprising a plurality of actuating unitshaving vibrating diaphragms associated therewith, tubular membersassociated with said diaphragms and adapted to form resonating chambers,said chambers being of different lengths and spherical resonatorslocated at the antinoda-l points in said chambers, said chambers andresonators being tuned to dif ferent notes comprising an octave in thechromatic scale for selectively amplifying waves of frequenciescorresponding to the iotes of said scale while suppressing waves ofother frequencies.

Signed at New York, in the county of New York and State of New York,this 28rd day of May, A. D. 1927.

MILLER REESE HUTCHISON.

